import math

l = map(float, raw_input().split())
dist = math.sqrt((l[0] - l[2])**2 + (l[1] - l[3])**2)
print dist import math math l = map(float, raw_input().split()) l map(float, raw_input().split()) map float raw_input().split() ().split () raw_input split dist = math.sqrt((l[0] - l[2])**2 + (l[1] - l[3])**2) dist math.sqrt((l[0] - l[2])**2 + (l[1] - l[3])**2) math.sqrt math sqrt (l[0] - l[2])**2 + (l[1] - l[3])**2 (l[0] - l[2])**2 l[0] - l[2] l[0] l 0 l[2] l 2 2 (l[1] - l[3])**2 l[1] - l[3] l[1] l 1 l[3] l 3 2 print dist = math.sqrt((l[0] - l[2])**2 + (l[1] - l[3])**2) math.sqrt((l[0] - l[2])**2 + (l[1] - l[3])**2) dist l = map(float, raw_input().split()) map(float, raw_input().split()) l
import math

l = map(float, raw_input().split())
dist = math.sqrt((l[0] - l[2])**2 + (l[1] - l[3])**2)
print dist